Method and system for treatment of deposition reactor

ABSTRACT

A system and method for treating a deposition reactor are disclosed. The system and method remove or mitigate formation of residue in a gas-phase reactor used to deposit doped metal films, such as aluminum-doped titanium carbide films or aluminum-doped tantalum carbide films. The method includes a step of exposing a reaction chamber to a treatment reactant that mitigates formation of species that lead to residue formation.

CROSS-REFERENCE TO RELATED APPLICATIONS

This Divisional Application claims priority to U.S. patent applicationSer. No. 14/166,462, entitled “METHOD AND SYSTEM FOR TREATMENT OFDEPOSITION REACTOR,” filed Jan. 18, 2014, which claims the benefit ofU.S. Provisional Application No. 61/759,990 entitled “METHOD AND SYSTEMFOR TREATMENT OF DEPOSITION REACTOR,” filed Feb. 1, 2013, thedisclosures of which are incorporated by reference herein.

FIELD OF INVENTION

The disclosure generally relates to methods and systems for treatingdeposition reactors. More particularly, exemplary embodiments of thepresent disclosure relate to methods and systems for mitigating orremoving buildup in gas-phase deposition reactors.

BACKGROUND OF THE DISCLOSURE

Doped metal films, e.g., doped metal carbides, nitrides, borides, andsilicides, such as aluminum-doped metal carbides, may be used for avariety of applications. For example, aluminum-doped titanium carbideand similar materials may be used for gate electrodes in metal oxidefield effect transistors (MOSFETs) or insulated gated field effecttransistors (IGFETs), such as complementary metal oxide semiconductor(CMOS) devices, as a barrier layer or fill material for semiconductor orsimilar electronic devices, or as coatings in other applications.

When used as a layer of an electronic device or as a coating, the dopedmetal films are typically deposited using gas-phase depositiontechniques, such as chemical vapor deposition techniques, includingatomic layer deposition. Precursors for the gas-phase deposition ofteninclude an organometallic compound (e.g., including aluminum) and ametal halide compound (e.g., including titanium or tantalum).Unfortunately, a decomposition temperature of the organometalliccompound can be much lower (e.g., more than 200° C. lower) than thetemperature of formation of the desired doped metal film. As a result,precursor decomposition products or residue may form in the depositionreaction chamber during a deposition process. The residue may, in turn,create particles, which result in defects in layers deposited using thereactor. In addition, some of the decomposition products may undergopolymerization in the presence of the metal halide compound, and thepolymerization products may result in additional defects in thedeposited layers. A number of defects within a deposited layer generallycorrelates to an amount of material deposited within the reactor; thenumber of defects within a layer generally increases as a number ofdeposition runs or amount of material deposited increases.

To mitigate the number of defects in the deposited layer, the reactormay be purged with an inert gas for an extended period of time, on theorder of hours, after a certain amount of material is deposited or anumber of substrates have been processed. This extended purge processsignificantly reduces the throughput of the deposition reactor andincreases the cost of operation of the reactor.

Accordingly, improved methods and systems for treating a depositionreactor to reduce or mitigate particle formation—such as particlesresulting from buildup of precursor decomposition products of materialsused to deposit doped metal films—are desired.

SUMMARY OF THE DISCLOSURE

Various embodiments of the present disclosure provide an improved methodand system for removing or mitigating the formation of residue in adeposition reactor or otherwise transforming the residue, such that itgenerates fewer particles. More particularly, exemplary systems andmethods mitigate formation of, transform, or remove residue resultingfrom the use of one or more precursors used in the deposition of dopedmetal films, such as metal films including carbon, boron, silicon,nitrogen, aluminum, or any combination thereof, in a gas-phasedeposition reactor. While the ways in which the various drawbacks of theprior art are discussed in greater detail below, in general, the methodand system use a gas-phase reactant to mitigate the formation of,transform, or remove unwanted residue within a reactor chamber. Bymitigating the formation of, transforming, or removing the unwantedresidue, fewer particles are formed within the reactor and thus fewerdefects are formed within deposited films. In addition, substratethroughput of the reactor is increased and the cost of operating thereactor is decreased.

In accordance with various embodiments of the disclosure, a method oftreating a reactor includes the steps of providing a metal halidechemistry to a reaction chamber of the deposition reactor, providing ametal CVD precursor selected from the group consisting of organometalliccompound chemistry and aluminum CVD compound chemistry to the reactionchamber, forming a doped metal film, providing a treatment reactantchemistry to the reaction chamber, exposing the reaction chamber to thetreatment reactant chemistry to mitigate particle formation of particlescomprising decomposition products of the metal CVD precursor (e.g., bymitigating residue buildup or by transforming the residue to materialthat is less likely to form particles within the reactor), and purgingthe reaction chamber. Deposition steps of the method may be repeated todeposit a desired amount of doped metal film or process a desired numberof substrates and then treat then reactor with the treatment reactant.In accordance with exemplary aspects of these embodiments, the treatmentreactant source comprises a compound selected from the group consistingof compounds comprising one or more hydrogen atoms and compoundscomprising a halogen (e.g., chlorine, HCl). In accordance with variousaspects, the treatment reactant source comprises a compound selectedfrom the group consisting of ammonia, hydrogen, silane, methane, siliconhydrides, boron hydrides, halosilanes, haloboranes, alkenes (e.g.,ethylene), alkynes, and hydrazine and its derivatives, such as alkylhydrazines etc. And, in accordance with yet further aspects, thetreatment reactant source comprises a decomposition product of the metalCVD source. The treatment reactant may be exposed to remote or directthermal or plasma activation to form activated species.

In accordance with further exemplary embodiments of the disclosure, asystem for treating a deposition reactor includes a reactor comprising areaction chamber, a metal halide source fluidly coupled to the reactor,a metal CVD source selected from the group consisting of one or more oforganometallic compounds and aluminum CVD compounds fluidly coupled tothe reactor, a treatment reactant source coupled to the reactor, and avacuum pump coupled to the reactor. The system may include direct orremote plasma and/or thermal excitation devices to provide activatedreactant species to the reaction chamber. In accordance with exemplaryaspects of these embodiments, the treatment reactant source comprises acompound selected from the group consisting of compounds comprising oneor more hydrogen atoms and compounds comprising a halogen (e.g.,chlorine, HCl). In accordance with various aspects, the treatmentreactant source comprises a compound selected from the group consistingof ammonia, hydrogen, silane, methane, silicon hydrides, boron hydrides,halosilanes, haloboranes, alkenes (e.g., ethylene), alkynes, andhydrazine and its derivatives, such as alkyl hydrazines etc. And, inaccordance with yet further aspects, the treatment reactant sourcecomprises a decomposition product of the metal CVD source.

In accordance with yet additional embodiments of the invention, a methodof treating a deposition reactor includes the steps of providing a metalhalide chemistry to a reaction chamber for a period of time, after thestep of providing a metal halide chemistry to a reaction chamber for aperiod of time, providing a treatment reactant chemistry to the reactionchamber for a period of time, and during or after providing a treatmentreactant chemistry to the reaction chamber for a period of time,providing a metal CVD precursor chemistry to the reaction chamber toform a layer of doped metal. In this case, particle formation ismitigated (e.g., via mitigation of residue formation or viadensification of the residue) during the deposition step and any residuethat forms may be removed during and optionally after the depositionprocess. The treatment reactant may be introduced with the metal CVDprecursor chemistry or before the introduction of the metal CVDprecursor. In accordance with exemplary aspects of these embodiments, atreatment reactant chemistry comprises one or more of hydrogen compoundsincluding one or more hydrogen atoms (e.g., hydrogen, HCl, silane,methane, ethylene, and the like) and compounds including a halogen(e.g., chlorine, HCl). The treatment reactant may be exposed to remoteor direct thermal or plasma activation to form activated species. Inaccordance with additional aspects of these embodiments, the step ofproviding a treatment reactant chemistry to the reaction chamberincludes providing a source of a decomposition product of theorganometallic compounds or the aluminum CVD compounds.

Both the foregoing summary and the following detailed description areexemplary and explanatory only and are not restrictive of the disclosureor the claimed invention.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

A more complete understanding of the embodiments of the presentdisclosure may be derived by referring to the detailed description andclaims when considered in connection with the following illustrativefigures.

FIG. 1 illustrates a system in accordance with various exemplaryembodiments of the disclosure.

FIG. 2 illustrates a method in accordance with exemplary embodiments ofthe disclosure.

FIG. 3 illustrates another method in accordance with exemplaryembodiments of the disclosure.

FIG. 4 illustrates a number of defects on a substrate based on a numberof substrates processed with no treatment.

FIG. 5 illustrates a number of defects on a substrate based on a numberof substrates processed using the treatment described herein.

It will be appreciated that elements in the figures are illustrated forsimplicity and clarity and have not necessarily been drawn to scale. Forexample, the dimensions of some of the elements in the figures may beexaggerated relative to other elements to help to improve understandingof illustrated embodiments of the present disclosure.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS OF THE INVENTION

The description of exemplary embodiments of methods and systems providedbelow is merely exemplary and is intended for purposes of illustrationonly; the following description is not intended to limit the scope ofthe disclosure or the claims. Moreover, recitation of multipleembodiments having stated features is not intended to exclude otherembodiments having additional features or other embodimentsincorporating different combinations of the stated features.

The method and system described herein can be used to mitigate formationof, remove, and/or transform residue in a reactor used to deposit dopedmetal films (e.g., films including carbon, boron, silicon, and/ornitrogen) that otherwise buildups and/or generates particles during adeposition process. Use of the methods and systems described hereinresults in a reduction of particle formation from residue and thereforeresults in higher throughput and in a lower cost of operation ofdeposition reactors, compared to reactors that are merely purged aftersimilar deposition processes.

Turning now to FIG. 1, a system 100, for mitigating deposition residuebuildup, as described herein, is illustrated. System 100 includes areactor 102, including a reaction chamber 104, a substrate holder 106,and a gas distribution system 108; a metal halide source 110; a metalchemical vapor deposition (CVD) source 112; a treatment reactant source114; lines 116, 118, 120 connecting sources 110-114 to reactor 102;valves 122, 124 and 126 interposed between the sources 110-114 andreactor 102; a vacuum pump 128, and optionally a carrier and/or purgegas source 130 coupled to reactor 102 via line 132 and valve 134.

Reactor 102 may be a standalone reactor or part of a cluster tool.Further, reactor 102 may be dedicated to doped metal deposition andtreatment processes as described herein, or reactor 102 may be used forother processes—e.g., for other layer deposition and/or etch processing.For example, reactor 102 may include a reactor typically used forphysical vapor deposition (PVD), chemical vapor deposition (CVD), and/oratomic layer deposition (ALD) processing, and may include remote ordirect thermal excitation, direct plasma, and/or remote plasmaapparatus. Using thermal or plasma activation apparatus during adeposition or treatment process creates excited molecules or speciesfrom one or more of sources 110-114 to enhance the reactivity of thereactants from sources 110-114. By way of one example, reactor 102includes a reactor suitable for ALD deposition. An exemplary ALD reactorsuitable for system 100 is described in U.S. Pat. No. 8,152,922, thecontents of which are hereby incorporated herein by reference, to theextent such contents do not conflict with the present disclosure.

Substrate holder 106 is designed to hold a substrate or workpiece 136 inplace during processing. In accordance with various exemplaryembodiments, holder 106 may form part of a direct plasma circuit.Additionally or alternatively, holder 106 may be heated, cooled, or beat ambient process temperature during processing.

Although gas distribution system 108 is illustrated in block form, gasdistribution system 108 may be relatively complex and be designed to mixvapor (gas) from sources 110 and/or 112 and carrier/purge gas from oneor more sources, such as gas source 130, prior to distributing the gasmixture to remainder of reactor 102. Further, system 108 may beconfigured to provide vertical (as illustrated) or horizontal flow ofgasses to the chamber 104. An exemplary gas distribution system isdescribed in U.S. Pat. No. 8,152,922. By way of example, distributionsystem 108 may include a showerhead.

Metal halide source 110 includes one or more gases, or materials thatbecome gaseous, that include a metal and a halide. Exemplary metalsinclude titanium, tantalum, and niobium. Exemplary halides includechlorine and bromine. Source 110 may include, for example, titaniumchloride (e.g., TiCl₄), tantalum chloride (e.g., TaCl₅), and niobiumchloride (e.g., NbCl₅). Gas from source 110 may be exposed to a thermaland/or remote plasma and/or direct plasma source to form activated orexcited species, such as ions and/or radicals including one or more ofchlorine, titanium, tantalum, and niobium. The term “activated species”includes the precursor and any ions and/or radicals than may form duringexposure of the precursor to any thermal and/or plasma process. Further,the term “chemistry,” when used in connection with a compound, includesthe compound and any activated specie(s), whether or not the compound(e.g., a reactant) has been exposed to thermal or plasma activation.

Metal CVD source 112 includes one or more gases, or materials thatbecome gaseous, that react with or form reactive species that react withcompounds or species from metal halide source 110 to form a depositedlayer of metal-doped film, such as a layer of aluminum-doped titaniumcarbide or aluminum-doped tantalum carbide, other carbines, nitride,silicides, or borides. Metal CVD source 112 may include, for example,organometallic compounds and/or aluminum CVD compounds, such as alanecompounds. Exemplary suitable organometallic compounds includetrimethylaluminum (TMA), triethylaluminum (TEA), triisobutylaluminum(TIBA), diethylaluminum chloride (DEACL), diethylaluminum hydride(DMAH), and tritertiarybutylaluminum (TTBA). Exemplary aluminum CVDalane compounds include trimethylamine alane (TMAA), triethylamine alane(TEAA), dimethyl ethylamine alane (DMEAA), trimethylaminealane borane(TMAAB), and methylpyrrolidine alane (MPA).

Use of organometallic compounds and alane compounds may be advantageous,because such compounds allow for atomic layer deposition, which allows,precise, conformal, self-limiting deposition of layers of desiredmaterial. However, the organic precursors are susceptible todecomposition at or below film deposition temperatures. Indeed, some ofthe precursors decompose at temperatures 200° C. (or more) less than thetemperature of formation of the film. As a result, the compounds maydecompose into undesired products prior to reaching substrate 136,resulting in residue formation within chamber 104 for example at or neargas distribution system 108, such as a showerhead. As noted above, theresidue formation may, in turn lead to particle formation, which causesdefects in the deposited metal films.

For example, many of the organometallic compounds may undergo abeta-hydride elimination reaction, in which an alkyl group bonded to ametal center is converted into a corresponding metal hydride and analkene compound. The formation of the alkene compound, particularly ator near gas distribution system 108, can result in residue buildup,which includes organic and inorganic materials. In addition, thedecomposition products can polymerize, e.g., in the presence of speciesfrom metal halide source 110, which may result in additional oralternative residue formation.

Gas from source 112 may be exposed to a thermal and/or a direct plasmasource and/or a remote plasma source to form activated species, such asions and/or radicals.

Treatment reactant source 114 includes one or more gases, or materialsthat become gaseous, that include a compound or species that mitigatesformation of residue within a reactor and/or that transforms the residuein a manner that generates less particles—e.g., by densifying theresidue. Exemplary compounds and species can react with a halogen on ahalogen (e.g., Cl)-terminated molecule (e.g., on a deposited film) tomitigate formation of undesired decomposition products. Treatmentreactant source 114 may include, for example, a compound selected fromthe group consisting of compounds comprising one or more hydrogen atomsand compounds comprising a halogen (e.g., chlorine, HCl). In accordancewith various aspects, the treatment reactant source comprises a compoundselected from the group consisting of ammonia, hydrogen, silane,methane, silicon hydrides, boron hydrides, halosilanes, haloboranes,alkenes (e.g., ethylene), alkynes, and hydrazine and its derivatives,such as alkyl hydrazines etc. And, in accordance with yet furtheraspects, the treatment reactant source comprises a decomposition productof the metal CVD source, e.g., a beta hydride elimination product of themetal CVD source.

Gas from source 114 may be exposed to a thermal and/or a remote plasmaand/or a direct plasma source to form activated or excited species, suchas ions and/or radicals including one or more of hydrogen and/orchlorine and/or other activated species.

Carrier or inert source 130 includes one or more gases, or materialsthat become gaseous, that are relatively unreactive in reactor 102.Exemplary carrier and inert gasses include nitrogen, argon, helium, andany combinations thereof

FIG. 2 illustrates a method 200 of treating a reactor in accordance withexemplary embodiments of the disclosure. Method 200 includes the stepsof: providing a metal halide chemistry (step 202), providing a metal CVDprecursor chemistry (step 204), forming a doped metal film (step 206),providing a treatment reactant chemistry (step 208), exposing thereaction chamber to the treatment reactant chemistry (step 210),optionally purging the reactor (step 212), and, if the desired amount ofmaterial has not been deposited (step 214), repeating steps 202-212, andif the desired amount of material has been deposited (step 214), theprocess is complete (step 216). Although not separately illustrated, asubstrate or workpiece may be removed from the reaction chamber beforetreatment step 210, such that the film on the workpiece is not exposedto the treatment reactant chemistry. Alternatively, the substrate may beexposed to the treatment reactant chemistry.

Step 202 includes providing metal halide chemistry to a reaction chamberand step 204 includes providing a metal CVD precursor chemistry to areaction chamber. Steps 202 and 204 may be performed in any order or beperformed simultaneously. Further, although illustrated with only tworeactant sources, exemplary methods may include the use of more than tworeactants.

The metal halide chemistry may include any of the compounds describedabove in connection with metal halide source 110. During step 202, themetal halide source may be exposed to a thermal activation processand/or a remote and/or direct plasma source to create metal halidesource chemistry that includes activate species. Similarly, the metalCVD precursor may include any compound noted above in connection withmetal CVD source 112. And, during step 204, the metal CVD precursor maybe exposed to a thermal activation process and/or a remote and/or directplasma source to create metal CVD source chemistry including activatedspecies.

During step 206, a metal film is formed. The metal film may include, forexample, aluminum, silicon, and/or boron doped titanium carbide,aluminum, silicon, and/or boron doped tantalum carbide, and/or aluminum,silicon, and/or boron doped niobium carbide, or other metal filmsincluding one or more of C, Si, B, or N.

During step 208, a treatment reactant chemistry to mitigate formation ofresidue and/or to densify the residue and/or to transform the residue toform fewer particles within a reaction chamber is introduced into thereaction chamber. The reactant chemistry may include any of thecompounds noted above in connection with treatment reactant source 114,and the reactant from a source may be exposed to thermal and/or plasmaactivation as described herein to form treatment reactant chemistryincluding activated species.

By way of examples, the treatment reactant chemistry may includehydrogen gas, and the hydrogen gas may be introduced to a reactionchamber (e.g., chamber 104) via a gas distribution system (e.g., system108). Additionally or alternatively, hydrogen gas may be exposed to aremote plasma to form treatment reactant chemistry including activatedspecies, such as hydrogen radicals. In accordance with exemplaryaspects, the remote plasma is configured, such that the activatedspecies can reach and react with material on the surface of the gasdistribution system (e.g., a showerhead), as well as within holes of thesystem near the surface. In addition or as an alternative, step 208 mayinclude providing a halogen, such as chlorine, or a halogen activatespecies, such as chlorine radicals, to the reaction chamber to mitigateformation of residue within the reaction chamber.

In accordance with other embodiments, the treatment reactant chemistryincludes ammonia, which may or may not by subjected to thermal and/ordirect and/or remote plasma activation as described herein. The ammoniais thought to react with a halogen (e.g., chlorine)-terminated surfaceof deposited material and mitigate formation of decomposition productswithin a reaction chamber.

Exemplary conditions for an ammonium residue reactant process includedepositing about 1250 Å carbide, followed by a 10 min exposure of NH₃,followed by a 20 min purge (remove residue NH₃), followed by depositingabout 1250 Å carbide, followed by about 10 min exposure of NH₃, followedby about 20 min purge (remove residue NH₃). The 1250 Å carbide may bedeposited onto, for example, 25 wafers at 50 Å each (one lot of wafers).

It is thought that this process transforms the residue in the reactor toprovide better adhesion, lowering stress or even making it lesssusceptible to oxidation to prevent this residual film from breaking offthe reactor surface and landing on the wafer-thus reducing on waferdefect levels.

Although illustrated as including a decision or determination step 214,method 200 may be configured to automatically run a predetermined numberof cycles of steps 202-212. For example, method 200 may be configured torun 1, 2, 3, 4, 5, or 50 number of cycles of steps 202-212 and complete(step 216) upon the conclusion of step 208 of the last cycle.Alternatively, steps 202-212 may be repeated based until a predeterminedamount of doped metal film is deposited. For example, the steps 202-212may be run until an accumulated film thickness of about 20 Å to about1250 Å or about 5 Å to about 5000 Å is reached.

FIGS. 4 and 5 illustrate a number of defects counted on a particle meteron a surface of a substrate when a reactor is not treated (FIG. 4) andwhen the reactor is treated (FIG. 5) in accordance with method 200, withammonia as the treatment reactant chemistry, under the conditions notedabove.

FIG. 3 illustrates another method 300 in accordance with additionalexemplary embodiments of the disclosure. Method 300 includes the stepsof providing a metal halide chemistry (step 302), providing a metal CVDprecursor chemistry (step 304), providing treatment reactant chemistry(step 306), forming a doped metal film (step 308), determining whether adesired amount of material has been deposited (step 310) and completingthe process (step 312) if a desired amount of material has beendeposited and repeating steps 302-310 if a desired amount of materialhas not been deposited. Although not illustrated, method 300 may includea purge step (similar to step 212) prior to step 312.

Steps 302 and 304 may be the same as steps 202 and 204, except, inaccordance with exemplary aspects of these embodiments, step 302 isperformed prior to step 304. And, in accordance with further aspects,step 306 is performed after step 302 and prior to or simultaneous withstep 304. By way of example, a metal halide chemistry from a metalhalide source may be introduced to a reaction chamber for a period oftime (e.g., a pulse of about 800 ms) during step 302. Then, during step306, a treatment reactant, such as hydrogen, activated hydrogen, silane,activated silane, ethylene, and/or activated ethylene is introduced tothe reaction chamber for a period of time. After or during step 306, themetal CVD reactant chemistry is introduced to the reaction chamber—e.g.,for about 3.5 sec. exposure—to form a doped metal film. Using a pulse ofthe treatment reactant chemistry during step 306, prior to or duringstep 304, is thought to reduce a number of halide-terminated species ona surface of deposited material and therefore reduce or eliminateresidue formation.

Although exemplary embodiments of the present disclosure are set forthherein, it should be appreciated that the disclosure is not so limited.For example, although the system and method are described in connectionwith various specific chemistries, the disclosure is not necessarilylimited to these chemistries. Various modifications, variations, andenhancements of the system and method set forth herein may be madewithout departing from the spirit and scope of the present disclosure.

What is claimed is:
 1. A system for treating as reaction chamber, thesystem comprising: a reactor comprising a reaction chamber; a metalhalide source fluidly coupled to the reactor; a metal CVD sourceselected from the group consisting of one or more of organometalliccompounds and aluminum CVD compounds fluidly coupled to the reactor; atreatment reactant source coupled to the reactor; and a vacuum pumpcoupled to the reactor.
 2. The system of claim 1, further comprising aplasma source, wherein treatment reactant from the treatment reactantsource is exposed to the plasma source to form one or more excitedtreatment reactant species.
 3. The system of claim 1, further comprisinga thermal excitation source, wherein treatment reactant from thetreatment reactant source is exposed to the thermal excitation source toform one or more excited treatment reactant species.
 4. The system ofclaim 1, wherein the treatment reactant source comprises one or morecompounds selected from the group of compounds comprising one or morehydrogen atoms and compounds comprising a halogen.
 5. The system ofclaim 1, wherein the treatment reactant source comprises one or more ofammonia, hydrogen, silane, methane, silicon hydrides, boron hydrides,halosilanes, haloboranes, alkenes, alkynes, and hydrazine and itsderivatives.
 6. The system of claim 1, wherein the treatment reactantsource comprises a decomposition product of the CVD source.